net: ethernet: 8390: axnet_cs: Document unused parameter 'txqueue'

net: ethernet: 8390: axnet_cs: Document unused parameter 'txqueue'

Fixes the following W=1 kernel build warning(s):

 drivers/net/ethernet/8390/axnet_cs.c:907: warning: Function parameter or member 'txqueue' not described in 'axnet_tx_timeout'

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Martin Habets <mhabets@solarflare.com>
Cc: Shannon Nelson <snelson@pensando.io>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: William Lee <william@asix.com.tw>
Cc: "A. Hinds --" <dahinds@users.sourceforge.net>
Cc: reached at <becker@scyld.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>